(NH4)(2)[Mg-4(H2O)(18)(H2W12O42)]center dot 10H(2)O, a new compound containing chains formed by magnesium and paradodecahedral tungstate ions

A new ammonium magnesium paradodecatungstate decahydrate, namely diammonium octadecaaquahydrogentetramagnesiododecatungstate decahydrate, (NH4)(2)[Mg- 4(H2O)(18)(H2W12O42)]. 10H(2)O, was prepared by the reaction of (NH4)(10)[H 2W12O42]. 4H(2)O with MgCl2 in aqueous solution. The skeleton of the parado decatungstate ion, [H2W12O42](10-), is basically the same as those in the k nown paradodecatungstates. It consists of 12 interconnected WO6 octahedra a nd its centre is located at a crystallographic inversion centre. Both indep endent Mg atoms are octahedrally coordinated by six O atoms. One magnesium octahedron shares an O atom with a paradodecatungstate group and the other magnesium octahedron shares two O atoms, each with different paradodecatung state groups, to form a one-dimensional [Mg-4(H2O)(18)(H2W12O42)](n)(2n-) c hain along the b direction.